it is a little inefficient but it makes for a much happier work environment. >> how many hours are there in a mars day? >> 24 hours and 40 minutes. >> bill: so then you have to calculate that. >> what happens is your day starts 40 minutes later and it gets weird when it gets like 2:00 in the morning. >> bill: all right now we want to talk about mars. first, i have to ask you about the earlier in the week, maybe it was last week, i guess announcement dr. begel about finding ice on the polar caps of mercury. i don't get this. this is the hottest of the planets, is it not? and why do they have ice and why is our ice melting? is there something wrong with this picture? >> no, it's not. it is also one of the coldest planets because one side is almost always toward the sun. one side is always in space. you've got this dichotomy of a really hot surface and a really cold surface. >> bill: it doesn't rotate? >> it rotates about once every 90 days so one side is able to cool off very quickly because it is radiating. so you've got places at the polls where it never gets hot. son and it acts as a co